Theoretically speaking, the NDVI value is expressed as the digital count between from-1 to +1. But the calculated NDVI taken by CCD camera for the vegetation object were generally represented the digital counts from 0.8 to 0.1. According to the weather condition and distance range between camera and object, this calculated value of NDVI has a different digital count in spite of the same target. This is due to effect of path-radiance. The authors proposed a method to remove path radiance from the data of CCD camera. The correlation coefficient of the proposed model using multivariate regression analysis is 0.98. By this model, NDVI can be revised as Estimate Normalized Difference Vegetation Index, called by ENDVI.